Browsing by Author "Christou, Stavroula Y."
Now showing items 1-18 of 18
-
Article
Deactivation of Pd/Ce 0.5Zr 0.5O 2 model three-way catalyst by P, Ca and Zn deposition
Christou, Stavroula Y.; García-Rodríguez, S.; Fierro, José Luis García; Efstathiou, Angelos M. (2012)The negative effects of P, P-Ca and P-Zn deposition on the surface of a model 1wt% Pd/Ce 0.5Zr 0.5O 2 " three-way" catalyst (TWC) on its structural, morphological, textural, oxygen storage and release, and catalytic ...
-
Article
Dynamics of oxygen storage and release on commercial aged Pd-Rh three-way catalysts and their characterization by transient experiments
Lambrou, Panayiota S.; Costa, Costas N.; Christou, Stavroula Y.; Efstathiou, Angelos M. (2004)The present work has provided new fundamental information on the effects of aging (mileage, km) of a commercial Pd-Rh (9:1, w/w) three-way catalyst (TWC) on (a) the H 2 chemisorption, (b) the redox properties of washcoat ...
-
Article
Effect of thermal aging on the transient kinetics of oxygen storage and release of commercial Cex Zr1-x O2-based solids
Christou, Stavroula Y.; Bradshaw, H.; Butler, C.; Darab, J.; Efstathiou, Angelos M. (2009)The use of powerful analytical methodologies for the evaluation of the performance of commercial oxygen storage materials based on oxygen transient isothermal isotopic exchange experiments is illustrated in this study. Ce ...
-
Article
The effects of P-poisoning of CexZr1-xO2 on the transient oxygen storage and release kinetics
Christou, Stavroula Y.; Efstathiou, Angelos M. (2013)The present work reports on the investigation of the effects of chemical poisoning of CexZr1-xO2 solids by phosphorous (P) on the kinetics of oxygen storage and release (OSR) of the thus derived P-contaminated solids, as ...
-
Article
Effects of Pd particle size on the rates of oxygen back-spillover and CO oxidation under dynamic oxygen storage and release measurements over Pd/CeO2 catalysts
Christou, Stavroula Y.; Efstathiou, Angelos M. (2007)A kinetic mathematical model has been applied to investigate for the first time the effects of Pd particle size on the rates of oxygen back-spillover and CO oxidation during Oxygen Storage Capacity (OSC) measurements under ...
-
Article
The effects of the use of weak organic acids on the improvement of oxygen storage and release properties of aged commercial three-way catalysts
Lambrou, Panayiota S.; Christou, Stavroula Y.; Fotopoulos, Apostolos P.; Foti, F. K.; Angelidis, Thomas N.; Efstathiou, Angelos M. (2005)The efficiency of weak organic acid solutions for improving the oxygen storage and release properties of aged commercial three-way catalysts (TWC) has been investigated. For the first time, three candidate leaching solutions, ...
-
Article
Efficient in-situ regeneration method of the catalytic activity of aged TWC
Christou, Stavroula Y.; Efstathiou, Angelos M. (2007)The expansion of durability of deactivated "three-way" catalysts (TWCs) used in gasoline-driven cars by applying efficient, economically viable and environmentally friendly methods for the in situ regeneration of their ...
-
Article
Influence of oxychlorination treatments on the redox and oxygen storage and release properties of thermally aged Pd-Rh/CexZr1-xO 2/Al2O3 model three-way catalysts
Daley, R. A.; Christou, Stavroula Y.; Efstathiou, Angelos M.; Anderson, J. A. (2005)Model Pd-Rh/Al2O3 three-way catalysts with and without CexZr1-xO2 as oxygen storage component have been compared in their fresh, thermally aged and oxychlorinated treated surface states to determine the potential regenerating ...
-
Article
Mathematical modeling of the oxygen storage capacity phenomenon studied by CO pulse transient experiments over Pd/CeO2 catalyst
Costa, Costas N.; Christou, Stavroula Y.; Georgiou, Georgios C.; Efstathiou, Angelos M. (2003)A mathematical model has been developed for the first time to study the oxygen storage capacity (OSC) phenomenon by the CO pulse injection technique over a 1 wt% Pd/CeO2 model catalyst in the 500-700°C range. A two-step ...
-
Article
Mathematical modeling of the oxygen storage capacity phenomenon studied by CO pulse transient experiments over Pd/CeO2 catalystAAA
Costa, Costas N.; Christou, Stavroula Y.; Georgiou, Georgios C.; Efstathiou, Angelos M. (2003)A mathematical model has been developed for the first time to study the oxygen storage capacity (OSC) phenomenon by the CO pulse injection technique over a 1 wt% Pd/CeO2 model catalyst in the 500-700°C range. A two-step ...
-
Article
Reactivation of an aged commercial three-way catalyst by oxalic and citric acid washing
Christou, Stavroula Y.; Birgersson, H.; Fierro, José Luis García; Efstathiou, Angelos M. (2006)The efficiency of dilute oxalic and citric acid solutions on improving the oxygen storage capacity (OSC) and catalytic activity of a severely aged (83 000 km) commercial three-way catalyst (TWC) has been investigated. ...
-
Article
Reactivation of severely aged commercial three-way catalysts by washing with weak EDTA and oxalic acid solutions
Christou, Stavroula Y.; Birgersson, H.; Efstathiou, Angelos M. (2007)Ethylene diamine tetraacetic acid (EDTA) which is a well-known reagent for its metal extraction efficiency was studied for the first time towards the improvement of the catalytic activity and oxygen storage and release ...
-
Article
Regeneration of aged commercial three-way catalysts using CI-containing reagents
Christou, Stavroula Y.; Efstathiou, Angelos M. (2013)The present work is focused on applying washing treatments using Cl-containing reagents, such as di-chloroacetic acid (DCA) for the first time, and 1,2-di-chloropropane, DCP (0.1 M) solutions in regaining the activity and ...
-
Article
Regeneration of aged commercial three-way catalytic converters
Christou, Stavroula Y.; Gåsste, J.; Karlsson, H. L.; Fierro, José Luis García; Efstathiou, Angelos M. (2009)The present work demonstrates for the first time that rejuvenation of the catalytic activity of full-scale aged commercial three-way catalytic (TWC) converters is feasible after treatment with weak oxalic acid solution ...
-
Article
Regeneration of thermally aged Pt-Rh/CexZr1-xO2-Al2O3 model three-way catalysts by oxychlorination treatments
Anderson, J. A.; Daley, R. A.; Christou, Stavroula Y.; Efstathiou, Angelos M. (2006)Pt-Rh/CexZr1-xO2-Al2O3 with 0.6 and 1.0 wt.% noble metal loadings were prepared and characterized for their metal dispersion with respect to CexZr1-xO2-free Pt-Rh/Al2O3 in fresh, thermally aged and oxychlorinated states. ...
-
Article
Regeneration of three-way automobile catalysts using biodegradable metal chelating agent-S, S-ethylenediamine disuccinic acid (S, S-EDDS)
Subramanian, B.; Christou, Stavroula Y.; Efstathiou, Angelos M.; Namboodiri, V.; Dionysiou, Dionysios Demetriou D. (2011)Regeneration of the activity of three-way catalytic converters (TWCs) was tested for the first time using a biodegradable metal chelating agent (S, S-ethylenediamine disuccinic acid (S, S-EDDS). The efficiency of this novel ...
-
Article
Suppression of the oxygen storage and release kinetics in Ce0.5Zr0.5O2 induced by P, Ca and Zn chemical poisoning
Christou, Stavroula Y.; Álvarez-Galván, M. C.; Fierro, José Luis García; Efstathiou, Angelos M. (2011)The present investigation concerns for the first time the understanding of the individual and combined effects of phosphorous with calcium or zinc deposited on a Ce0.5Zr0.5O2 solid followed by calcination in 20%O2/He at ...
-
Article
A two-step reaction mechanism of oxygen release from Pd/CeO2: Mathematical modelling based on step gas concentration experiments
Christou, Stavroula Y.; Costa, Costas N.; Efstathiou, Angelos M. (2004)A mathematical model was developed to study the transient release of oxygen from a 1 wt % Pd/CeO2 catalyst in the 450°-550°C range based on alternate step concentration switches between CO and O2. The proposed mathematical ...